Editor's note: this story has been updated to include comment from the Port of Portland.
Opponents of the expansion at the Hillsboro Airport hit another road block Thursday.
The U.S. Ninth Circuit Court of Appeals denied a challenge to environmental impact studies connected to the airport's new runway.
In an opinion written by Judge Richard Clifton, the panel found the runway project "would have no significant impact on the environment."
The panel found the airport and the FAA "complied with the requirements" of airport-improvement legislation and did not break any laws, hide findings or act suspiciously.
The airport is managed by the Port of Portland, which developed a new master plan to expand its Hillsboro facility and build a new runway for smaller aircraft. The new runway would allow the airport to prioritize traffic on the longer runways and reduce backup both in the air and on the ground.
Because the improvements were funded in part by FAA grants, according to the court opinion, "environmental effects of the project had to be considered."
The Port produced its own environmental assessment in 2010, which was immediately opposed by several individuals and the Oregon Avation Watch. The court initially rejected some of the groups' concerns, but did ask the Port for additional assessment, which the Port provided in 2014.
The runway was completed in 2015.
The latest opinion addresses the charge that the FAA didn't dig deep enough to examine environmental concerns. Petitioners also argued an even more thorough environmental impact statement was needed — something the Port denied in 2014 — and argued the FAA didn't do enough to ensure the runway fit with plans of surrounding agencies.
Clifton's opinion looks at each of the petitioners' concerns, which were argued and submitted on Oct. 5, 2016.
Opponents argued Port forecasts for growth in the next decade underestimate total air traffic and do not include a response from Hillsboro Air Academy, a pilot training facility.
Clifton stated the FAA did receive a response from the training program and found the Port's forecasts appropriate.
Opponents also voiced concerns about environmental impacts and took issue with lower predicted emission levels despite a forecast increase in traffic.
The petitioners specifically argued the airport failed to monitor the amount of lead in the soil and water around the facility. But the latest assessment indicates the new runway would have little effect on the lead in the area, Clifton stated — less than 4 percent in 2021.
Opponents also argued the FAA didn't address concerns about the effects of lead in children, but the assessment specifically pointed to emissions levels well below the EPA's limit, Clifton stated.
The Port is in the process of updating its master plan for the Hillsboro facility. The last master plan, from 2005 to 2015, included the new airstrip and mainly focused on airfield infrastructure.
In a statement to the Tribune on Aug. 4, the a spokesperson for the Port of Portland said the Port was "pleased with the court's decision, which puts this long-time issue to rest."
The statement highlighted the Port's response to initial challenges in 2011, and pointed to the Port's efforts to address environmental concerns.
The attorney for the petitioners, Sean Malone of Eugene, did not immediately return request for comment.